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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/pipeline/document_source_out.h"
#include <fmt/format.h>
#include "mongo/db/curop_failpoint_helpers.h"
#include "mongo/db/ops/write_ops.h"
#include "mongo/db/pipeline/document_path_support.h"
#include "mongo/logv2/log.h"
#include "mongo/rpc/get_status_from_command_result.h"
#include "mongo/util/destructor_guard.h"
#include "mongo/util/fail_point.h"
#include "mongo/util/uuid.h"
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kQuery
namespace mongo {
using namespace fmt::literals;
MONGO_FAIL_POINT_DEFINE(hangWhileBuildingDocumentSourceOutBatch);
MONGO_FAIL_POINT_DEFINE(outWaitAfterTempCollectionCreation);
REGISTER_DOCUMENT_SOURCE(out,
DocumentSourceOut::LiteParsed::parse,
DocumentSourceOut::createFromBson,
AllowedWithApiStrict::kAlways);
DocumentSourceOut::~DocumentSourceOut() {
DESTRUCTOR_GUARD(
// Make sure we drop the temp collection if anything goes wrong. Errors are ignored
// here because nothing can be done about them. Additionally, if this fails and the
// collection is left behind, it will be cleaned up next time the server is started.
if (_tempNs.size()) {
auto cleanupClient =
pExpCtx->opCtx->getServiceContext()->makeClient("$out_replace_coll_cleanup");
AlternativeClientRegion acr(cleanupClient);
// Create a new operation context so that any interrupts on the current operation will
// not affect the dropCollection operation below.
auto cleanupOpCtx = cc().makeOperationContext();
DocumentSourceWriteBlock writeBlock(cleanupOpCtx.get());
pExpCtx->mongoProcessInterface->dropCollection(cleanupOpCtx.get(), _tempNs);
});
}
NamespaceString DocumentSourceOut::parseNsFromElem(const BSONElement& spec,
const DatabaseName& defaultDB) {
if (spec.type() == BSONType::String) {
return NamespaceString(defaultDB, spec.valueStringData());
} else if (spec.type() == BSONType::Object) {
auto nsObj = spec.Obj();
uassert(16994,
str::stream() << "If an object is passed to " << kStageName
<< " it must have exactly 2 fields: 'db' and 'coll'",
nsObj.nFields() == 2 && nsObj.hasField("coll") && nsObj.hasField("db"));
return NamespaceString(defaultDB.tenantId(), nsObj["db"].String(), nsObj["coll"].String());
} else {
uassert(16990,
"{} only supports a string or object argument, but found {}"_format(
kStageName, typeName(spec.type())),
spec.type() == BSONType::String);
}
MONGO_UNREACHABLE;
}
std::unique_ptr<DocumentSourceOut::LiteParsed> DocumentSourceOut::LiteParsed::parse(
const NamespaceString& nss, const BSONElement& spec) {
NamespaceString targetNss = parseNsFromElem(spec, nss.dbName());
uassert(ErrorCodes::InvalidNamespace,
"Invalid {} target namespace, {}"_format(kStageName, targetNss.ns()),
targetNss.isValid());
return std::make_unique<DocumentSourceOut::LiteParsed>(spec.fieldName(), std::move(targetNss));
}
void DocumentSourceOut::initialize() {
DocumentSourceWriteBlock writeBlock(pExpCtx->opCtx);
const auto& outputNs = getOutputNs();
// We will write all results into a temporary collection, then rename the temporary collection
// to be the target collection once we are done.
// Note that this temporary collection name is used by MongoMirror and thus should not be
// changed without consultation.
_tempNs = NamespaceString(outputNs.tenantId(),
str::stream() << outputNs.dbName().toString() << ".tmp.agg_out."
<< UUID::gen());
// Save the original collection options and index specs so we can check they didn't change
// during computation.
_originalOutOptions =
// The uuid field is considered an option, but cannot be passed to createCollection.
pExpCtx->mongoProcessInterface->getCollectionOptions(pExpCtx->opCtx, outputNs)
.removeField("uuid");
_originalIndexes = pExpCtx->mongoProcessInterface->getIndexSpecs(
pExpCtx->opCtx, outputNs, false /* includeBuildUUIDs */);
// Check if it's capped to make sure we have a chance of succeeding before we do all the work.
// If the collection becomes capped during processing, the collection options will have changed,
// and the $out will fail.
uassert(17152,
"namespace '{}' is capped so it can't be used for {}"_format(outputNs.ns(), kStageName),
_originalOutOptions["capped"].eoo());
{
BSONObjBuilder cmd;
cmd << "create" << _tempNs.coll();
cmd << "temp" << true;
cmd.appendElementsUnique(_originalOutOptions);
pExpCtx->mongoProcessInterface->createCollection(
pExpCtx->opCtx, _tempNs.dbName(), cmd.done());
}
CurOpFailpointHelpers::waitWhileFailPointEnabled(
&outWaitAfterTempCollectionCreation,
pExpCtx->opCtx,
"outWaitAfterTempCollectionCreation",
[]() {
LOGV2(20901,
"Hanging aggregation due to 'outWaitAfterTempCollectionCreation' failpoint");
});
if (_originalIndexes.empty()) {
return;
}
// Copy the indexes of the output collection to the temp collection.
try {
std::vector<BSONObj> tempNsIndexes = {std::begin(_originalIndexes),
std::end(_originalIndexes)};
pExpCtx->mongoProcessInterface->createIndexesOnEmptyCollection(
pExpCtx->opCtx, _tempNs, tempNsIndexes);
} catch (DBException& ex) {
ex.addContext("Copying indexes for $out failed");
throw;
}
}
void DocumentSourceOut::finalize() {
DocumentSourceWriteBlock writeBlock(pExpCtx->opCtx);
const auto& outputNs = getOutputNs();
pExpCtx->mongoProcessInterface->renameIfOptionsAndIndexesHaveNotChanged(pExpCtx->opCtx,
_tempNs,
outputNs,
true /* dropTarget */,
false /* stayTemp */,
_originalOutOptions,
_originalIndexes);
// The rename succeeded, so the temp collection no longer exists.
_tempNs = {};
}
boost::intrusive_ptr<DocumentSource> DocumentSourceOut::create(
NamespaceString outputNs, const boost::intrusive_ptr<ExpressionContext>& expCtx) {
uassert(ErrorCodes::OperationNotSupportedInTransaction,
"{} cannot be used in a transaction"_format(kStageName),
!expCtx->opCtx->inMultiDocumentTransaction());
uassert(ErrorCodes::InvalidNamespace,
"Invalid {} target namespace, {}"_format(kStageName, outputNs.ns()),
outputNs.isValid());
uassert(17385,
"Can't {} to special collection: {}"_format(kStageName, outputNs.coll()),
!outputNs.isSystem());
uassert(31321,
"Can't {} to internal database: {}"_format(kStageName, outputNs.db()),
!outputNs.isOnInternalDb());
return new DocumentSourceOut(std::move(outputNs), expCtx);
}
boost::intrusive_ptr<DocumentSource> DocumentSourceOut::createFromBson(
BSONElement elem, const boost::intrusive_ptr<ExpressionContext>& expCtx) {
auto targetNS = parseNsFromElem(elem, expCtx->ns.dbName());
return create(targetNS, expCtx);
}
Value DocumentSourceOut::serialize(boost::optional<ExplainOptions::Verbosity> explain) const {
// Do not include the tenantId in the serialized 'outputNs'.
return Value(
DOC(kStageName << DOC("db" << _outputNs.dbName().db() << "coll" << _outputNs.coll())));
}
void DocumentSourceOut::waitWhileFailPointEnabled() {
CurOpFailpointHelpers::waitWhileFailPointEnabled(
&hangWhileBuildingDocumentSourceOutBatch,
pExpCtx->opCtx,
"hangWhileBuildingDocumentSourceOutBatch",
[]() {
LOGV2(20902,
"Hanging aggregation due to 'hangWhileBuildingDocumentSourceOutBatch' failpoint");
});
}
} // namespace mongo
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